Binary coding device



C. H. HOEPPNER BINARY CODING DEVICE Nov. 4, 1952 5 Sheets-Sheet l Filed March 22, 1950 6)/ Arm@ N0V 4, 1952 c. H. HoEPPNr-:R

BINARY GODIN@ DEVICE 3 Sheets-Sheet 2 Filed March 22, 1950 MT /Il I lll irlll, HNI E M Il H 6 w 7 0 Z 8 7 7 L fm 7/ w/ m HHIIWM .wh .WLQQ- MQQ- .MQ MSO; MQQB MH QOL an .v E. W NP P. m WHUA H. w W ov- CB Patented Nov. 4, 1952 BINARY ooniNo DEVICE Conrad H. Hoeppner, Waltham, Mass., assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application March 22, 1950, Serial No. 151,131

8 Claims.

so converted is relatively easily transmitted from station to station and is in a useful form for direct use in digital computers.

One limitation in the amount of such information which may be converted to the binary code and the accuracy with which intelligence may be recorded is the speed of binary counters used in code conversion. Conventional binary counting circuits as, for example multivibrators, have a counting frequency limitation of between four and six megacycles. For rates above this range conventional counting circuits are generally unsatisfactory. Thus, if the nature of intelligence makes it desirable, for example, to use a code having 128 cycles within a twenty microsecond interval or intelligence period, a counting frequency or 6.4 megacycles would be required which is beyond the practical range of counters in the past.

Pursuant to the present invention, counting frequencies of over eighteen megacycles may be successfully used and recorded with a high degree of accuracy. This is achieved by providing a delay line tapped at suitable intervals to form a counter for those digits which change too rapidly for conventional counting devices. The delay line may then be followed by conventional counters, such as, for example multivibrator counters, for any remaining digits in the code. Also, by tapping the delay line at the above intervals, the effective counting frequency is also greatly increased, thus permitting the use of a relatively low frequency oscillator for generating the counting pulses.

A present embodiment incorporates the above in a novel arrangement for periodically sampling and recording a varying voltage intelligence signal in thebinary code. In this embodiment, a seven digit code is used. A dual control grid tube, herein called a coincidence tube, is used for each of the digits for obtaining at any selected instant the count on the counters. three digits in this instance are supplied by suitable taps along the above-mentioned delay line. The remaining four digits are supplied from conventional counting circuits. The rising voltage of a saw-tooth voltage generator is compared to the r The rst tor.

` voltage intelligence signal. The time interval ror the voltage of the saw-tooth generator to reach that of the voltage signal provides the intelligence interval which is converted into the binary code in the present embodiment. To insure accuracy in interval determination, a quantizing arrangement is used with the saw-tooth voltage generator. This arrangement provides for a small, abrupt quantum or voltage peak to occur in the rising voltage pattern of the saw-tooth genera- A peak of this type is made to occur once for each counting pulse in the binary counters and located on the rising saw-tooth voltage at a point corresponding to the time interval represented by the pulse. Thus, the comparison of the saw-tooth voltage to the signal voltage will 0ccur in discrete steps such that a sampling pulse resulting from the comparison will occur only at one of these peaks and thus in synchronism with the counting picture produced by the counters at the coincidence tubes. The present embodiment achieves this quantization scheme by coupling points of the above-mentioned delay line corresponding to the individual counting pulses to the saw-tooth voltage generator in a manner to produce these quanta peaks at corresponding time intervals in the rising voltage of the saw-tooth generator.

A second embodiment of the invention is adapted for converting pulse position and pulse time intelligence signals into binary code. In this embodiment, a synchronism pulse of the pulse intelligence is made to cause counting pulses of a suitable frequency to appear at coincidence tubes as in the first embodiment. The signal or information pulse of the pulse intelligence is resynchronized by a separate multivibrator, gate and blocking oscillator arrangement so as to produce a triggering pulse for sampling the counter reading on the coincidence in synchronism with a distinct count representing the interval between the above two pulses.

The foregoing and other objects and features of the invention will become more apparent from the following description taken in connection with the accompanying drawings wherein:

. Fig. 1 is a schematic view of an embodiment of the yinvention for converting varying voltage intelligence to binary code;

Fig. 2 is a graph illustrating the pulse picture at one rof the control grids of the coincidence tubes in the invention;

Fig. 3 is a graph illustrating a small portion of the rising voltage of the saw-tooth generator with synchronizing peaks thereon; and

Fig. 4 is a mock diagram, which, taken in conection with a portion of Fig. 1, comprises a second embodiment of the invention particularly adapted to convert pulse position and pulse time modulation intelligence to binary code.

Referring to Fig. 1 in more detail, dual control grid, tubes I2, I4, I6, I8., 20rv and 22, re.- spectively, as` for example high vacuum tubesv of the 6AS6 type and herein called coincidence tubes, are used for obtaining a sampling binary code count at any desired instant. Each tube represents a digit in the binary code. Inthis instance, the first three digits` represented by coincidence tubes I0, I2 and |,4are. obtained from` suitable taps 24, 26, 28, 30, 32, 34 and 36,k preferably at equal time delay intervals, on delay line 38. Delay line 38, as will' be seen, has preterably a time delay such that, when a counting pulse reaches the end of the delay line, another counting pulse is just entering` thev line at point 39. Control grid. 40 of. coincidence tube |`0 is connected to points 24 28, 32 and' 36 on delay line 36. Control grid 42 of coincidence tube I2 is connected to points. 26, 28, 34v and 36 of delay line 38, and control grid 44. is connected to p-ointsr 30, 32, 34 and: 36 of delay line 38. Unidirectional current devicesfsuch as crystals or diodes 46 are used in the linesv connecting. thev above points on delay line 38 and` control grids 40, 42 and 44 of thecoincidence tubesytopreve'nt short circuit.- ing. The delay line 38 passes through a suitable gate 46 which.l may be a singleelectron tube gatev to counting circuits 46, `50, 52 and 54 which in this instance. are bistabley multivibrator circuits arranged in conventional manner, as binary counters. Counting circuits 48,50,v 52 and 54 are connectedr tocontrol grids 56,. 5,8, 60 and 62 of coincidence tubes |6,. I8 20 and. 22, respectively. In this manner, aseven digit counting ar-r rangement` is achieved with the first eight numbers being effected fromthe. delay line 38y in the coincidence tubes.L I0, I2 and I4. The seven digits. represent. a maximum count of |21. A higher count may be: obtained by adding addi.- tional counting circuits and corresponding coincidence tubes. When the; gatey 46 is open, an oscillator 64 combined With pulse former 66, producesA pulses 68,A preferably ofA the square wave type` which travel. down the. delay line 38 and through. gate 46. to the` binary counters 48,. 50, 52- and 54. Because.l of the connection of control grids 40, 42. and 44 of. coincidencetubesy I0, |2 and I4, respectively, on. the, delay line 38, each pulse 68 will appear as,` four pulses l0 at controlv grid 40, four pulses; 'I2 at control grid 42, and four pulses I.4.atv control grid 44, shown in Fig. 2- and representing a count. of seven. The picture at grids 56, 58, and 60, respectively, because of counting circuits. 48,. 50 and 52. will appear as curves 1:63, 'I8l and 80 in Fig,r 2. The. curve for control grid 62: has not been shown because the count representedy in Fig. 2 is not suiciently high to produce any change at the grid 62. Control grids 82, 84, 86, 88, 90, 92 and 94 of the coincidence tubes are connected to line 96. Line 96 is connected byline 9I to a peak amplier 96 from whichv at periodic intervals to be hereinafter described sampling pulses |00 occur inV line 96. These pulses will appear at control grids` 8-2, 84, 66, 88', 90, 92 and 94 simultaneously. If, at the time the sampling pulse |00 appears atv the coincidence tubes, a counting pulse from delay line 38.012 counting circuits 48, 50, 52 andV 54 also exists at the other control grid, those tubes having such two coincident pulses will cause current to flow so as to produce signal pulses at their anodes which are registered in those of the signal registering crcuits |02, |04, |06, |08, I|0, |I2 and ||4 connected to the anodes of the particular coincidence tubes. The register circuits are in this instancev monostable multivibrators. A monostable multivibrator inherently' flops back to its stable state at the end of a delay periodv after it has been made to operate by a triggering pulse. The delay may be varied by adjusting its timing capacitance and resistance circuit, for example. In this. instance,r the. monostable multivibrators are. arranged` with sufcient delay to permit recording of. the registered signals from the coincidence tubes or a suitable recorder IIB. A suitable multichannel recorder for this purpose may consist of an inductance coil ||5 connected to each of the register circuits |02, |04, |06, |08, |10, ||2, and ||4. Those of the register circuits which receive signal pulsesfrom the coincidence tubes are energized to cause current to flow through the corresponding inductance coils ||5 vvhich,v through their cores |`I'I, produce a magnetized spot. in a coating ||9 ofY magnetic Inaterial on ay recording sheet. By moving the' recording sheet as in the direction of the arrow for: each successive sampling, a permanent recordv of the binary. numbers may be obtained.

Referring to Fig. 2, if' a. sampling pulse |00 occurred in line 96 with its leading` edge at a time represented by line |06, coincidence` tube. I0 would not be in proper conditionto conduct;v coincidence tube I2 would conduct; coincidence tube. I4 would. not conduct; coincidence tube I6 would' conduct; and coincidence tubes I6, 20 and 22 would not conduct. In this instance, only the monostable multivibrators |04 and |08 connected to the anodes of coincidence tubes I2 and I6 would register av signal which, in turn, would be recorded on recorder I I6, If a 0 ora blank space is used to represent those multivibratorsy whichk do not register a signal,A and a dot or a 1 is usedto represent thosemultivibrators which do regis.-

ter a signal, the appropriate code picture for the.

above example may be shown as 0 1 0 1v 0- 0 0 which, is this instance, is the-binary code for a count of ten. In like. manner, other counts in this code would appear as follows:

o oV o o 0w 0 o o 1 o 0 o 0- o o 1 o 1 o 0 o` o o 2 1 1 0 o o o o 3 o o 1 o o o o 4 o o o 1 o o o a o o' o o 1 o 0 1o 1 1 1 1 1 1 1 12'1v Thus any number fromA Ot'hrough 127 may be obtained iny thepresentembodiment. It should be noted that, while the above digits readv froml left to right, they may bev arranged to read from right to left or in any desired sequence by re-V arranging lead lines fromf the registers to recorder |'|6 or from the counters to ther control grids. ofv the coincidence tubes.`

A frequency divider ||8'having frequency of a much smaller order thanV the oscillator 64,v is led through a pulse former |20 from which signal pulses |22, preferably of the square Wave type, actuate a gate which in: this instance is a bistable multivibrator gate |24 which, in turn, produces a square-Wave |26 in line, |28 leading to a sawtooth generator |30. The lea-dingr edge |32 of the square wave |26 causes the saw-tooth voltage generator to produce a rising voltage in line |34 leading to a comparator |36 to which is led an intelligence voltage signal |38 by line |40 whose voltage is to be sampled at periodic points and converted to the binary code. When the voltage in the line |34 has risen to a point slightly above that of the voltage in the signal |38, the comparator |36 produces a pulse which is amplified by peak amplifier 98 and appearing as sampling pulse |09 in line 96. One such comparator may consist of a diode |42 whose anode |44 is connected to saw-tooth voltage generator |30 by line |34 and to whose cathode |46 is led the voltage signal |98 through line |40 and resistance |48. The cathode |45I may be suitably coupled to the peak amplier 98 through a capacitance |50. The pulse |90 is also led from the peak amplier 98 through line |52 back to the bistable multivibrator |24 so as to terminate the gating pulse |26 as at |54, thereby stopping the saw-tooth voltage generator |30.

At the instant that square wave |28 was started by the multivibrator |24, a similar square wave |518 is started through line |58 to open the gate 46 so as to admit counting pulses from the pulse former 66 and delay line 38 through the counting circuits 48, 50, 52 and 54. Pulse |22 and pulse 68 are preferably so timed that the pulse 68 will be just starting from the point 39 at the beginning of the delay line 38 when the pulse |22 actuates multivibrator |24. This may be done by inserting a suitable length of signal delay line |60, similar to delay line 38 in front of the point 39. In this manner, the start of voltage generation of the saw-tooth voltage generator |30 is synchronized with the start of counting pulses in the delay line 38 and counting circuits 48, 50, 52 and 54.

The gate 46 remains open for the duration of square wave 58. The square wave |56 is terminated similarly to square wave |26. Termination is effected at |62 when the bistable multivibrator |24 is energized through line |52 by pulse |90. This prevents further counting pulses from going beyond the gate |46 and permits resetting of counters 48, 50, 52 and 64 in preparation for the next count. The sampling pulse |00, besides operating multivibrator |24 and obtaining a reading of the counter as explained above, also passes on through line |64 to a. signal delay device such as a delay multivibrator |66, where a short delay occurs to insure no interference in obtaining the binary code count on the coincidence tubes. After the short delay, a pulse from the delay multivibrator |66 passes through line |68 to a conventional clearing circuit |10 which resets the counting circuits 48, 50, 52 and 54 to a zero condition. Since the counting circuits 43, 58, 52 and 54 are in this instance bistable multivibrators, the clearing circuit may include an amplifier to amplify the pulse in line |68 and lines running to trigger those tubes in the multivibrators which represent a zero counting condition. After resetting in this manner, the apparatus is again ready to start a new cycle for sampling the signal voltage |38.

Since the sampling pulse |00 has a nite time duration it may interfere with the accuracy of the code readings. If, for example, this time duration is represented in Fig. 2 by the space between lines |12 and |14 the pulse |00 would overlap count intervals in the coincidence tubes, as shown, and thereby interfere with the accuracy of the code readings. One method of minimizing .this is to make the pulses 68. and

therefore pulses 10, 12, etc. (FigjZ). narrower as shown by dotted lines |16 and |18, thus leaving small gaps as shown between dotted lines |16 and |18. Another more preferable method, and that used in the present embodiment, is a quantizing arrangement wherein the pulse |00 is synchronized with the pulses 10, 12 and 14. This arrangement is provided by connecting through unidirectional current devices |11, as crystals or diodes, the points 24, 26, 28, 30, 32, 34 and 36 of the delay line 38 by line |19 to the saw-tooth voltage generator |30 so that the rising voltage output of the saw-tooth generator in line |34 has small voltage quanta units or peaks occurring periodically once for each counting pulse;

shown substantially at as the voltage picture at anode |44. This may be seen more clearly in Fig. 3 where |82 is a small portion of the linear saw-tooth voltage rise on which is superimposed the quanta peaks |84 which, in the instance shown, has reached a count of eleven. If, :for example, an 800 kilocycle oscillator is used as the oscillator 64, counting pulses will appear at anode |44 at the very rapid rate of 6.4 megacycles so that the portion of the saw-tooth wave. shown by |82, is actually less than two microseconds in duration. Therefore, for practical purposes, the portion of the signal voltage |38 appearing in this very short time may be represented by a straight line |38. The sampling pulse 00 will occur at the quantum peak |86. In this manner, it is seen that because of quanta peaks |84, sampling pulses |00 will occur at definite increments of time. The leading edge of the sampling pulse |00 may be thereby synchronized with the pulse picture at the coincidence tubes so as to fall, for example, at the line |06. In a count of one hundred the error will be less than one per cent. Y Assuming, for purposes of illustration, that the maximum voltage which might occur in signal |38 may be reached in twenty microseconds by the voltage from the saw-tooth voltage generator |30, it is desirable that the saw-tooth voltage generated have at lea-st a twenty microsecond interval. The frequency divider ||8 for providing pulses |22 for initiating the cycle should be a sufhciently small fraction of that of the frequency oscillator 64 so as to provide ample time for complete clearing and resetting of the apparatus between individual samplings. One such suitable frequency used was 1390 cycles per second which thereby provided for a reading approximately every 720 microseconds. Other freduencies may be used equally well.

By removing gate 46 so that the delay line 38 leads directly to counting circuit 48 and by replacing the circuits in the portion enclosed by dotted line |88 in Fig. 1 with circuits enclosed in dotted line |90 of Fig. 4, a second embodiment of the invention is produced which is particularly adapted for converting pulse time and pulse position modulation signals to binary code. Such intelligence consists of synchronizing and intelligence pulses, the interval between which, in this embodiment, is converted to binary code. In this embodiment, a xed frequency keyed oscillator |92 is connected at point a to pulse former 66. The oscillator |92 may have any suitable frequency, but, for purposes of illustration in this embodiment, has a frequency of 800 kilocycles. The oscillator |92 is turned on and ofi by a fbistable multivibrator |94. The ibistable multivibrator |94 is energized by a synchronizing pulse` 200 of thepulse position and pulse time modulation :intelligence through line 202 to start the'zoscillator i592. Countingpulses 68 :are thereby .rmade to pass through the Acounting lcircuits. An .intelligence pulse |96 lof the pulse position or pulse rtime modulation intelligence is then .led through .line 268 to energize another bistable multivibrator 2li) so as to opena 'gat-e2 l2 such as for example, a suitable'electron -tube gate. This permits lpulses from line V|89 which is connected at point b to line 2|4 to pass through gate 2|2. The rst'of thesejpulses energizesa third bistable multivibrator 2|6 which in `.turn opens a gate |28, which may be .similar .to gate 2|2. The pulses .from lati are therebyppermitted to flow in line 220 to a blocking oscillator 222. .As-aresult, only a rst of these pulses, as -a single `sampling pulse 224, passes from the-blocking oscillator 2212 to line 96 through lines 226 and 97 which areconnected at point c. .The sampling' pulse 224 is thereby in proper s ynchronism with thepulse picture at the vcoincidence tubes for obtaining binary lconversion as explained in the iirst embodiment. 'The intelligence pulse `|96 may thereby be considered .as .having been resynchronized Vfor :sampling purposes.

The intelligence pulse |96 also passes lthrough line |98 to cause the bistable multivibrator Sto stop the 'oscillator -|92inpreparation yfor another cycle similar to that explained above, andthe samplingpulse 22llalso appears through line .22.3 at `the .bistable multivibrators A2I|l and 2|?) so as to close :gates vill-'2 .and ;2 I8 `in preparation Yfor the next cycle.

.This :invention is Anot limited to the `particular' details -of construction and processes described, as many equivalents Will `suggest .themselves `to those Askilled .in the art. .It is accordingly desired :that :the appended claims .be given .a .broad interpretation commensurate with-.the-scope .of the .invention within the art.

What .fis claimed-is:

.1. A device for converting-the interval between two signal pulses .to binary code comprising meansfor'ieach or" the digits .in said-code responsive to two simultaneous signalpulses .for producing a code signal, means for generatingixed interval pulses, delay means arranged for making said pulses appear as pulse trains at Veach oi said responsive means .representing .the .more rapidly changing numbers in said code, the pattern .of the pulse train at each orsaid last-mentioned .responsive means being determined by said code, binary counting .means v:for 4receiving said pulses from said delay means and effecting appropriate pulses at the remaining numbers of said responsive means, means vresponsive to a nrst of said two signal` pulses for causing .generation of said Xed intervalpulses into said vdelay means; and means for making vthe otherof said two signal pulses appear substantially simultaneously at each of said responsive means, thereby producing code signals at those responsive means where a pulse of said vtrainsor said counters and vsaid other pulse vappear simultaneously.

`2. 'A system for converting the "interval between two signal pulses to'binary code comprising means for each ofthe digits in said --code responsive to two simultaneous signal'pulses for producing a code signal, means for 'generating fixed interval pulses, delay means arranged for making said pulses appear as'pulse'trains at each of'said responsive means representing the more tern ofthe pulse train-at each of sai-d last-mentimed-responsive means being .determined by said code, binary counting means for receiving said pulses :from ,said delay means .and .effecting appropriate pulses at the remaining .num-bers of said responsive means, means responsive to a first of said two signal pulses for causing generation of said xed interval pulses into said delay means, means for synchronizing .the other oi said two signal Apulses with the pulses appearing at-said responsive means, and means for making said synchronized pulse appear substantially simultaneously at each of said responsive means, thereby producing code signals .at those responsive means where a pulse .of said trains or said counters and said other' pulse appear simultaneously.

`.3. ,A systemor converting a signal voltage to binary. code comprising-means for each of the digits in said code responsive to two simultaneous signal pulses for producing a code signal, means for generating xed interval .pulses, delay means arrangedfor making said pulses appear as pulse trainsat each of said responsive means representing the more rapidly `'chang-ing numbers in said code, the pattern of the pulse train at each oi said last-mentioned responsive means being determinedby said codejbinary counting means iorreceiving said pulses from said delay means and effecting appropriate pulses at the remaining numberso'f said responsive means, time controlmeans responsive to said signal voltage for generatinga signal pulse at each of said firstmentioned .responsive means, thereby causing those of said first-mentioned responsive rmeans having simultaneously one of said .number pulses to produce code signals, and means for starting said time control means in known relation with the count in said delay and counting means.

4. A system for converting a signal 'voltage .to binary code comprising means foreach of the digitsin saidcode responsive to two simultaneous signal pulses for producing a code signal, means for generating .xed vinterval pulses, delay means arranged for making said pulses appear as pulse trainsiat .each of said responsive means representing .themore rapidly changing numbers in said code, .the pattern of the pulse train at each of said .last-mentioned responsive kmeans "being .determined .by said code, binary counting means for receiving .said pulses from said delay means and-effecting appropriate pulses at theremaning numbersof said responsive means, time control means .responsive to said signal voltage for generatinga .signalpulse at eachof said lfirst-mentioned .responsive means, thereby causing those of said.inst-mentioned'.responsive means having simultaneously one of said number lpulses toproducecode signals, means for causing said lastmentioned signal pulseto occur in synchronism with said numberpulses, and ,means for starting said .timecontrol means in known relation with thecountinvsaid .delay and counting means.

Q5. A system .for .converting ,a .signal voltage to binary .code comprising means foreach .of the digits Ain .said codev responsive to .two .simultaneous signal pulses for producing va-code signal, .means for generating .fixedinterval pulses, .delay means arrangedformaking said pulsesappear ,as pulse trains -at each of said responsive means representing themore rapidly changing numbers .in

said-code,l the Ypattern of thefpulsetrain at each of .said :last-mentioned responsivemeans being determined by said xcode, :binary counting ymeans for :receiving :said pulse'sfrom -saidfjclelay means Aand effecting appropriate pulses fat 4:the v.remaining' numbers of said responsive means, time control means responsive to said signal voltage for generating a signal pulse at each of said firstmentioned responsive means, thereby causing those of said first-mentioned responsive means having simultaneously one of said number pulses to produce code signals, means for causing said last-mentioned signal pulse to occur in synchronism With said number pulses, means for starting said time control means in known relation with the count in said delay and counting means, and means for resetting said counting means after said code signals.

6. A system for counting pulses and converting the count into code notation comprising: a counting pulse generator; a plurality of devices, corresponding, respectively, to each of the digits in the code, for producing code signals; means, receptive of the counting pulses from said generator and connected to the aforesaid devices corresponding to the lower order digits of the code, for applying to said last-mentioned devices patterns of pulses for each counting pulse entering said means; said patterns of pulses being determined by the code notation of the lower order digits of the number being counted; and means, receptive of the counting pulses from said first-named means and connected to the aforesaid devices corresponding to the higher order digits of the code, for applying to said last-mentioned devices appropriate pulses determined by the code notation of the higher order digits of the number being counted.

'7. A system for counting pulses and converting the count into code notation comprising: a counting pulse generator; a plurality of devices, corresponding, respectively, to each of the digits in the code, for producing code signals; a delay line, receptive of the counting pulses from said generator and connected at uniformly spaced points along the length thereof to the aforesaid devices corresponding to the lower order digits of the code, for applying to said last-mentioned devices patterns of pulses for each counting pulse entering said delay line; said patterns of pulses being determined by the code notation of the lower order digits of the number being counted; and means, receptive of the counting pulses from the end of said delay line and connected to the aforesaid devices corresponding to the higher order digits of the code, for applying to said last-mentioned devices appropriate pulses determined by the code notation of the higher order digits of the number being counted.

8. A system for counting pulses and converting the count into code notation comprising: a counting pulse generator; a timing pulse generator; means for synchronizing the operation of said timing pulse generator with the operation of said counting pulse generator; a plurality of devices, corresponding, respectively, to each of the digits in the code, for producing code signals; means, receptive of the counting pulses from said firstnamed generator and connected to the aforesaid devices corresponding to the lower order digits of the code, for applying to said last-mentioned devices during the interval of the timing pulse produced by said second-named generator patterns of pulses for each counting pulse entering said means; said patterns of pulses being determined by the code notation of the lower order digits of the number being counted; means, receptive of the counting pulses from said first-named means and connected to the aforesaid devices corresponding to the higher order digits of the code, for applying to said last-mentioned devices during the interval of the timing pulse produced by said second-named generator appropriate pulses determined by the code notation of the higher order digits of the number being counted and means for terminating the interval of said timing pulse and recording the code signals produced during said interval.

CONRAD H. HOEPPNER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,272,070 Reeves' Feb. 3, 1942 2,438,908 Goodall Apr. 6, 1948 2,485,821 Gloess et al Oct. 25, 1949 2,508,622 Pierce May 23, 1950 

